Microgel containing vulcanizable composition based on hydrogenated nitrile rubber

Abstract

A novel vulcanizable composition is provided, based on at least one hydrogenated nitrile rubber, on at least one peroxide, on at least one unsaturated carboxylic acid and/or salts thereof, and also on specific microgels. These vulcanizable compositions can be used to obtain vulcanized products which can in particular be used for drive belts, roll coverings, hoses and cables.

What is claimed is: 
     
       1. A vulcanizable composition comprising
 a) 100 parts by weight, based on 100 parts by weight of rubber, one or more hydrogenated nitrile rubbers, in which the Mooney viscosity (ML 1+4@100° C.) is in the range from 10 to 120 MU, where the Mooney viscosity is determined to ASTM standard D1646, which are co- or terpolymers based on at least one conjugated diene and at least one α,β-unsaturated nitrile monomer and optionally one additional copolymerizable monomer, in which the degree of hydrogenation of the diene units incorporated into the polymer is in the range from 95 to 100%, 
 b) from 5 to 80 parts by weight, based on 100 parts by weight of rubber, one or more unsaturated carboxylic acids and/or one or more salts thereof, and the unsaturated carboxylic acid is selected from the group consisting of methacrylic acid, acrylic acid, cinnamic acid, crotonic acid and itaconic acid and the salts are selected from the group consisting of sodium, potassium, magnesium, calcium, zinc, barium, aluminum, tin, zirconium and lithium, 
 c) from 0.2 to 8 parts by weight, based on 100 parts by weight of rubber, at least one peroxide and 
 d) at least one microgel having a glass transition temperature below −20° C. wherein the microgel is present in the composition and is present in an amount up to 50 parts by weight, based on 100 parts by weight of rubber, and 
 e) from 0 to 100 parts by weight based on 100 parts by weight of rubber optionally one or more conventional rubber additives. 
 
     
     
       2. The vulcanizable composition according to  claim 1 , wherein the component a) used comprises one or more hydrogenated nitrile rubbers in which the Mooney viscosity (ML 1+4 @ 100° C.) is in the range from 15 to 100 MU, where the Mooney viscosity is determined to ASTM standard D1646. 
     
     
       3. The vulcanizable composition according to  claim 1 , wherein the component b) used comprises one or more metal diacrylates and/or metal dimethacrylates. 
     
     
       4. The vulcanizable composition according to  claim 1 , wherein the component b) used comprises zinc diacrylate or zinc dimethacrylate. 
     
     
       5. The vulcanizable composition according to  claim 1 , wherein the component c) used comprises at least one peroxide selected from the group consisting of dicumyl peroxide, tert-butyl cumyl peroxide, bis(tert-butylperoxy-isopropyl)benzene, di-tert-butyl peroxide, 2,5-dimethylhexane 2,5-dihydroperoxide, 2,5-dimethylhex-3-yne 2,5-dihydroperoxide, dibenzoyl peroxide, bis(2,4-dichlorobenzoyl)peroxide, tert-butyl perbenzoate, butyl 4,4-di(tert-butylperoxy)valerate and 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane. 
     
     
       6. The vulcanizable composition according to  claim 1 , wherein the component d) used comprises at least one microgel whose glass transition temperature is in the range of from −80° C. to −50° C. and which is a crosslinked homopolymer or crosslinked random copolymer. 
     
     
       7. The vulcanizable composition according to  claim 1 , wherein the component d) used comprises at least one microgel whose glass transition temperature is in the range of from −80° C. to −50° C. and which has at least 70% by weight of fractions (“gel content”) insoluble in toluene at 23° C. 
     
     
       8. The vulcanizable composition according to  claim 1 , wherein the component d) used comprises at least one microgel whose glass transition temperature is in the range of from −80° C. to −50° C. and which has a swelling index (“SI”) in toluene at 23° C. of less than 80, where the swelling index is calculated from the weight of the solvent-containing microgel swollen for 24 hours in toluene at 23° C. (after centrifuging at 20 000 rpm) and the weight of the dry microgel by using the following formula: SI=wet weight of microgel/dry weight of microgel. 
     
     
       9. A process for the preparation of the vulcanizable compositions according to  claim 1 , wherein the components a, b, c and d are mixed with one another. 
     
     
       10. A process for the production of vulcanized products, wherein the vulcanizable composition according to  claim 1  is exposed to heat treatment. 
     
     
       11. The process according to  claim 9 , wherein the vulcanizable composition is exposed in molds to a temperature in the range from 120 to 200° C. 
     
     
       12. A vulcanized product comprising the composition according to  claim 1 , wherein components a, b, c & d are mixed with one another. 
     
     
       13. The vulcanized product according to  claim 12  in the form of a drive belt, a roll covering, a gasket, a hose or a cable. 
     
     
       14. The composition according to  claim 1 , wherein the microgel is present in the composition in an amount up to 10 parts by weight, based on 100 parts by weight of rubber.